Novel water-resistant, repulpable and hydrophilic paper having a soft feel

ABSTRACT

Novel water-resistant, repulpable and hydrophilic papers having a soft feel are prepared from paper pulps containing at least one resin (A) which improves the wet strength thereof and, optionally, at least one wet strength promoter (B), the paper pulps or papers prepared therefrom having been treated with a composition (D) comprising at least one polyorganosiloxane (C) which contains, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom, such functional group V comprising sterically hindered piperidinyl functional group(s).

CROSS-REFERENCE TO PRIORITY/PROVISIONAL APPLICATIONS

[0001] This application claims priority under 35 U.S.C. § 119 of FR 03/05102, filed Apr. 25, 2003, and of provisional application Ser. No. 60/485,109, filed Jul. 8, 2003, both hereby expressly incorporated by reference and both assigned to the assignee hereof. This application is also a continuation of said '109 provisional.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field of the Invention

[0003] The present invention relates to the field of absorbent paper and, in particular, to a novel water-resistant, repulpable and hydrophilic paper having a soft feel, and to a process for the manufacture of this paper.

[0004] 2. Description of Background and/or Related and/or Prior Art

[0005] For certain paper applications, in particular for an absorbent paper, it is necessary for the paper to retain, in the wet state, a portion of its dry strength. The wet strength of the paper is generally expressed by the ratio:

(BL wet/BL dry)×100

[0006] where:

[0007] BL wet is the breaking length of a strip of wet paper,

[0008] BL dry is the breaking length of a strip of dry paper.

[0009] Generally, paper possessing wet strength has a wet strength of greater than 5%.

[0010] In order to improve the mechanical properties of wet paper, it is common practice, at the stage of the manufacture of the paper, to incorporate resins into the body of the paper pulp in order to improve the wet strength of the paper.

[0011] For example, it is customary to use resins of the polyamidoamine-epichlorohydrin (PAE) type, resins of low molecular weight, resulting from the condensation of adipic acid and of diethylenetriamine, followed by a reaction of the condensation product with epichlorohydrin. This type of resin crosslinks to the cellulose fibers at neutral pH. These products are characterized by the presence of structures of azetidinium type. In order to obtain paper with an even higher wet strength, these resins have been combined with substances known as wet strength promoters, such as polymers with an anionic or amphoteric nature, for example, sodium carboxymethylcellulose (H. Espy, 1983, in Papermaker Research J., pp. 191-195), modified guar gum (CA-808,531 or U.S. Pat. No. 5,318,669) or an anionic or amphoteric latex of acrylic polymer type (FR-2,769,926).

[0012] However the use of resins in order to improve the wet strength of paper results in a major disadvantage, which is the loss of the feeling of softness to the touch because the paper becomes rougher. For applications in the field of absorbent paper, for example, paper towels, toilet paper, and the like, this loss of softness is a major impediment to the commercial introduction of the product in question. Furthermore, a paper manufactured from this type of resin is difficult to repulp (or recycle), which increases its manufacturing costs. Furthermore, ecologically, it is desirable to generate the minimum amount of waste.

[0013] The prior art represented by JP-6311943 provides a treatment of paper with a silicone emulsion based on diorganopolysiloxane comprising a specific group which is a linear aminoalkyl. However, the use of an aminated silicone enhances the water-repelling properties of the paper, which is harmful for the hydrophilic properties of the paper. Furthermore, this type of paper is difficult to repulp. This solution is therefore unacceptable for absorbent paper.

[0014] The papermaking industry therefore seeks novel solutions which make it possible to obtain repulpable absorbent or hydrophilic paper having a soft feel and which possesses wet strength.

SUMMARY OF THE INVENTION

[0015] It has now unexpectedly and surprisingly been determined that a specific class of aminated silicones exhibits noteworthy advantages with respect to the other known compounds of the prior art. Specifically, a novel water-resistant, repulpable and hydrophilic paper having a soft feel has now been developed based on a class of hindered aminated silicones which ameliorate or avoid the disadvantages of the abovementioned prior art. A process for the preparation of this paper has also been developed.

[0016] The present invention thus features a water-resistant, repulpable and hydrophilic paper having a soft feel.

DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OF THE INVENTION

[0017] More particularly according to the present invention, a novel water-resistant, repulpable and hydrophilic paper having a soft feel is prepared from a paper pulp comprising an effective amount of at least one resin (A) which improves the wet strength and optionally of at least one wet strength promoter (B), wherein the paper pulp or the paper is brought into contact with a composition (D) comprising at least one polyorganosiloxane (C) comprising, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom, the functional group V being a group with sterically hindered piperidinyl functional group(s) selected from the group consisting of the:

[0018] (a) groups of formula (I):

[0019] in which formula R⁴ is a divalent hydrocarbonaceous radical selected from among:

[0020] linear or branched alkylene radicals having 2 to 18 carbon atoms;

[0021] alkylenecarbonyl radicals, the linear or branched alkylene moiety of which having 2 to 20 carbon atoms;

[0022] alkylenecyclohexylene radicals, the linear or branched alkylene moiety of which having 2 to 12 carbon atoms and the cyclohexylene moiety of which comprises an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms;

[0023] radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals, which may be identical or different, are each an alkylene radical having 1 to 12 carbon atoms;

[0024] radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals are as defined above and one of them or both are substituted by one or two —OH group(s);

[0025] radicals of formula —R⁷—COO—R⁷— in which the R⁷ radicals are as defined above;

[0026] radicals of formula —R⁸—O—R⁹—O—CO—R⁸— in which the R⁸ and R⁹ radicals, which may be identical or different, are each an alkylene radical having 2 to 12 carbon atoms and the R⁹ radical is optionally substituted by a hydroxyl radical; U represents —O— or —NR¹⁰-, in which R¹⁰ is a hydrogen atom, a linear or branched alkyl radical having 1 to 6 carbon atoms or a divalent radical of formula:

[0027] in which R⁴ is as defined above, R⁵ and R⁶ are as defined below and R¹¹ is a linear or branched divalent alkylene radical having from 1 to 12 carbon atoms, one of the valency bonds (that of R¹¹) being connected to the atom of —NR¹⁰— and the other (that of R⁴) being connected to a silicon atom; the R⁵ radicals, which may be identical or different, are each a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; and the R⁶ radical is a hydrogen atom or R⁵ or 0;

[0028] (b) groups of formula (II):

[0029] in which formula R′⁴ is a trivalent radical of formula:

[0030] where m represents a number from 2 to 20, or a trivalent radical of formula:

[0031] where p represents a number from 2 to 20; U′ represents —O— or —NR¹²—, in which R¹² is a hydrogen atom or a linear or branched alkyl radical having 1 to 6 carbon atoms; and R⁵ and R⁶ have the same meanings as in formula (I).

[0032] According to the present invention, the term “effective amount of at least one resin (A) which improves the wet strength and optionally of at least one wet strength promoter (B)” is understood to mean the amount necessary and sufficient in order to obtain the desired effect. The amount will vary according to the type of paper (absorbent, superabsorbent, and the like); for example, useful amounts of resin (A) and of wet strength promoter (B) according to the invention, expressed on a dry basis with respect to the weight of dry paper fibers, generally range from 0.01% to 5%.

[0033] However, this ratio can be varied beyond this range if necessary.

[0034] The polyorganosiloxane (C) advantageously comprises the siloxyl units represented by the formula (III):

[0035] in which formula:

[0036] (1) the symbols Z, which may be identical or different, represent R¹ and/or V;

[0037] (2) the symbols R¹, R² and R³, which may be identical or different, each represent an optionally substituted, linear or branched, C₁-C₁₂ alkyl radical, an optionally substituted C₅-C₁₀ cycloalkyl radical, an optionally substituted C₆-C₁₈ aryl radical, an optionally substituted aralkyl radical or an —OR¹³ radical wherein R¹³ represents a hydrogen atom, a linear, branched or cyclic alkyl radical having from 1 to 15 carbon atoms or a hydrocarbonaceous group comprising an epoxide and/or polyether functional group;

[0038] (3) the symbols V are as defined above; and

[0039] (4) the number of siloxyl units without a V group ranges from 1 to 800, the number of siloxyl units with a V group ranges from 1 to 20, and 0≦w≦10 and 8≦y≦798.

[0040] According to a preferred embodiment, the polyorganosiloxane (C) of formula (III) is linear (w=0) and the symbols R¹, R² and R³ of the formula (III) are methyl groups.

[0041] According to another preferred embodiment, the functional groups V of the polyorganosiloxane (C) are defined by the formulae (I) and (II) in which the R⁵ groups are methyls.

[0042] More specifically, the polyorganosiloxane (C) according to the invention is a compound of following general formula (IV):

[0043] in which formula:

[0044] the various units are randomly distributed in the chain;

[0045] p represents a number greater than or equal to 0;

[0046] r represents a number greater than or equal to 0;

[0047] q represents a number greater than or equal to 1, preferably ranging from 1 to 20;

[0048] R′¹ represents a linear or branched alkyl radical having 1 to 18 carbon atoms;

[0049] the U, R⁴ and R⁶ groups are as defined above.

[0050] According to another preferred embodiment, the sum p+r ranges from 1 to 800.

[0051] Mention may be made, among the resins (A) which improve the wet strength according to the invention, in particular of cationic resins of polyamidoamine-epichlorohydrin (PAE) type or polyamide cationic resins with the Amres® trademark (for example, the resins Amres® 2747, Amres® 8855, Amres® 8870, Amres® HS-30, Amres® HP-25, Amres® MOC-3066, Amres® LA 12-2, Amres® C12, Amres® C20, Amres® C25, Amres® C28, Amres® X-184, Amres® C382, Amres® PR-335 CU, Amres® PR-247 HV and Amres® LOPR) sold by Georgia-Pacific Resins. Other such resins are disclosed in U.S. Pat. Nos. 3,372,086, 3,607,622, 3,914,155, 4,233,411, 3,556,932, 3,734,977, 4,722,964 and 5,567,798.

[0052] Preferably, the resin (A) which improves the wet strength is selected from the group consisting of cationic resins of polyamidoamine-epichlorohydrin type.

[0053] Mention may be made, among the wet strength promoters (B) according to the invention, of polymers with an anionic or amphoteric nature, such as sodium carboxymethylcellulose (described in the article by H. Espy, 1983, in Papermaker Research J., pp. 191-195), modified guar gum (disclosed in CA-808,531 and U.S. Pat. No. 5,318,669) and an anionic or amphoteric latex of acrylic polymer type (disclosed in FR-2,769,926).

[0054] The composition (D) comprising the polyorganosiloxane (C) can be prepared in numerous forms: liquid, gas or solid. In the case of a liquid preparation of the composition, this will advantageously be aqueous, i.e., in the solution, dispersion or emulsion form.

[0055] Preferably, the composition is prepared in the form of an aqueous emulsion. The paper is either impregnated with this composition or else the latter is either added to the paper pulp or applied to the paper during the process for the manufacture of the paper.

[0056] The aqueous emulsions are generally based on a mixture of oil and of water and are prepared according to conventional methods well known to those skilled in the art using surface-active agents. For example, the emulsions can be prepared by “direct” methods or by inversion. They are easy to prepare and their preparation does not require the use of equipment with a high stirring rate. Equipment with a normal stirring rate can be used.

[0057] Generally, the aqueous emulsions prepared in accordance with the invention preferably comprise from 20% to 90% by weight of water with respect to the total weight of the constituents of the emulsion, for better application when the composition is applied to the paper. These emulsions prove to be stable at ambient temperature.

[0058] The application to the paper of the composition (D) according to the invention can be carried out in highly varied forms. The applications can be carried out by immersion, coating, spraying, printing, padding or any other existing means.

[0059] The amount of polyorganosiloxane (C) deposited on the paper to be treated or added to the paper pulp varies according to the composition and the type of paper. Generally, the best results have been observed with an amount of polyorganosiloxane ranging from 0.1% to 10% by weight with respect to the weight of the dry matter to be treated.

[0060] The polyorganosiloxanes (C) defined above can be prepared according to various processes; for example: by redistribution or via a hydrosilylation reaction (see, for example, EP-388,321).

[0061] The present invention also features a process for the manufacture of a water-resistant, repulpable and hydrophilic paper having a soft feel in which a paper pulp, preferably a cellulose pulp, comprising an effective amount of at least one resin (A) which improves the wet strength and optionally of at least one wet strength promoter (B) is prepared, wherein the paper pulp or the paper is brought into contact with a composition comprising at least one polyorganosiloxane (C) as defined above.

[0062] This process exhibits the advantage of manufacturing a water-resistant, repulpable and hydrophilic paper having a soft feel. Another advantage associated with this process is the possibility of easily repulping the waste, thus lowering the production costs.

[0063] Examples of resin (A) which improves the wet strength which are of use according to the process of the invention are as described above.

[0064] Preferably, the resin (A) which improves the wet strength is selected from the group consisting of cationic resins of polyamidoamine-epichlorohydrin (PAE) type.

[0065] By way of illustration, the process for the manufacture of the paper according to the invention can be described by the stages a) to f) which, apart from the use of the composition (D) according to the invention, are known per se by one skilled in this art and are summarized thus:

[0066] a) The paper pulp is suspended in water inside “pulpers” in order to separate the fibers. After purification, the pulp is subjected to a “beating” operation, the aim of which is to hydrate the fibers so as to allow them to become entangled. It is then that inorganic fillers (calcium carbonate, kaolin, talc, titanium dioxide) and adjuvants (adhesives, retention aids, antifoaming agents, antislime agents, colorants, shading colorants, whitening agents, and the like), which will improve the characteristics of the paper, are added to the pulp. According to a first alternative form of the invention, it is at this first stage that the composition (D) according to the invention can be added to the paper pulp.

[0067] b) The pulp is again purified and then diluted and deaerated. The pulp is then distributed in the form of a jet over the entire width of a wire of a mechanical assembly known as a forming table. This wire is subjected to a spasmodic lateral to-and-fro movement which facilitates the homogeneous formation of the paper sheet and the dewatering thereof. The fibers very naturally have a tendency to align themselves in the direction of movement of the stock wave. The paper sheet comprises from 75% to 85% of water at its departure from the table.

[0068] c) In this stage, the percentage of water in the paper sheet is reduced to 60% or 70% by the pressing technique, which also makes it possible to increase the compactness and to improve the surface condition by mechanical action on the still very malleable sheet.

[0069] d) Subsequently, the paper sheet is dried using cast iron drums heated internally with steam.

[0070] e) A stage of coating the paper sheet is optionally carried out. The paper is coated with a composition based on starch and optionally on other materials, such as inorganic pigments (carbonate, talc, and the like), colorants, whitening agents, shading colorants and dispersing agents.

[0071] f) The surface of the paper can optionally be rendered even by means of polished steel rolls. The surface of the paper thus treated is rendered even by compression: the paper is said to be “finished” or “smoothed”.

[0072] According to a second alternative form of the process, the paper can be treated with the composition (D) according to the invention after stages d), e) and/or f).

[0073] The present invention also features the use of the composition (D) comprising at least one polyorganosiloxane (C) comprising, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom in the manufacture, by the wet route, of a water-resistant, repulpable and hydrophilic paper having a soft feel.

[0074] The present invention is particularly suitable for applications such as paper towels, toilet paper, household or sanitary absorbent paper, paper handkerchiefs or any other paper requiring good absorbent properties, good mechanical wet strength, a good aptitude for repulping and a soft feel.

[0075] In order to further illustrate the present invention and the advantages thereof, the following specific examples are given, it being understood that same are intended only as illustrative and in nowise limitative. In said examples to follow, all parts and percentages are given by weight, unless otherwise indicated.

EXAMPLES

[0076] The examples below illustrate the properties of the compositions comprising the polyorganosiloxanes according to the invention.

[0077] The papers used are as follows:

[0078] hand towels (small roll);

[0079] laboratory towels (large roll);

[0080] paper serviettes.

[0081] The technique for treating the paper which is used for the tests is the technique of impregnation by padding. For this, the polyorganosiloxanes are applied in the aqueous phase. The dilution of the emulsions is calculated so as to deposit 1% of dry silicone on the paper.

[0082] The polyorganosiloxanes are tested in the application in the form of an aqueous emulsion and the measurements of hydrophilicity and of evaluation of the feel are carried out according to the tests described below.

[0083] Feel Test:

[0084] After impregnating with the emulsion, the paper is dried by a heat treatment at 150° C. for 3 minutes and is conditioned for 24 hours (23±2° C., 60%±5% relative humidity).

[0085] The softness is evaluated by a group of testers who are requested to classify the paper samples from the roughest (minimum grade=1) to the softest (maximum grade=total number of samples).

[0086] Hydrophilicity Measurement:

[0087] The hydrophilicity measurements are given by the Tegewa test, in which the absorption time of a drop of water deposited at the surface of the paper is measured: The shorter the time, the more hydrophilic the paper.

[0088] Preparation of the Emulsions:

[0089] The silicone oils of the emulsions tested, E1 and E2 (invention), have the structure:

[0090] Emulsion E1: x=10 and y=700

[0091] Emulsion E2: x=2 and y=100.

[0092] The emulsion Cl (comparative) is an emulsion based on a silicone oil functionalized by a linear aminated functional group with the structure:

[0093] with x=1.5 and y=135.

[0094] The emulsions are prepared by employing an inversion emulsification method and have the following composition: 20 g of silicone oil tested, 8 g of surfactant (C13E6 fatty alcohol), an amount of glacial acetic acid stoichiometrically necessary for the neutralization of the amine, and the remainder to 100 g with water.

[0095] Results: Tegewa Test Feel Test Labo- Labo- Hand ratory Hand ratory Emulsions Towel Towel Serviette Towel Towel Serviette C1 30 min 30 min 40 min  8 12  7 E1 15 s  6 s 25 s  9  8  9 E2  3 s  3 s  4 s 10  7 11 Control  2 s  4 s  2 s  3  3  3 (untreated paper)

[0096] Each patent, patent application, publication and literature article/report cited or indicated herein is hereby expressly incorporated by reference.

[0097] While the invention has been described in terms of various specific and preferred embodiments, the skilled artisan will appreciate that various modifications, substitutions, omissions, and changes may be made without departing from the spirit thereof. Accordingly, it is intended that the scope of the present invention be limited solely by the scope of the following claims, including equivalents thereof. 

What is claimed is:
 1. Water-resistant, repulpable and hydrophilic paper having a soft feel comprising an effective amount of at least one resin (A) which improves the wet strength thereof, optionally, at least one wet strength promoter (B), and at least one polyorganosiloxane (C) which comprises, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom, the functional group V being a group with sterically hindered piperidinyl functional group(s) selected from the group consisting of the: (a) groups of formula (I):

in which formula R⁴ is a divalent hydrocarbonaceous radical selected from among: linear or branched alkylene radicals having 2 to 18 carbon atoms; alkylenecarbonyl radicals, the linear or branched alkylene moiety of which having 2 to 20 carbon atoms; alkylenecyclohexylene radicals, the linear or branched alkylene moiety of which having 2 to 12 carbon atoms and the cyclohexylene moiety of which comprises an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals, which may be identical or different, are each an alkylene radical having 1 to 12 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals are as defined above and one of them or both are substituted by one or two —OH group(s); radicals of formula —R⁷—COO—R⁷— in which the R⁷ radicals are as defined above; radicals of formula —R⁸—O—R⁹—O—CO—R⁸— in which the R⁸ and R⁹ radicals, which may be identical or different, are each an alkylene radical having 2 to 12 carbon atoms and the R⁹ radical is optionally substituted by a hydroxyl radical; U represents —O— or —NR¹⁰-, in which R¹⁰ is a hydrogen atom, a linear or branched alkyl radical having 1 to 6 carbon atoms or a divalent radical of formula:

in which R⁴ is as defined above, R⁵ and R⁶ are as defined below and R¹¹ is a linear or branched divalent alkylene radical having from 1 to 12 carbon atoms, one of the valency bonds (that of R¹¹) being connected to the atom of —NR¹⁰— and the other (that of R⁴) being connected to a silicon atom; the R⁵ radicals, which may be identical or different, are each a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; and the R⁶ radical is a hydrogen atom or R⁵ or 0; and (b) groups of formula (II):

in which formula R′⁴ is a trivalent radical of formula:

where m represents a number from 2 to 20, or a trivalent radical of formula:

where p represents a number from 2 to 20; U′ represents —O— or —NR¹²—, in which R¹² is a hydrogen atom or a linear or branched alkyl radical having 1 to 6 carbon atoms; and R⁵ and R⁶ have the same meanings as in formula (I).
 2. Water-resistant, repulpable and hydrophilic paper having a soft feel prepared from a paper pulp comprising an effective amount of at least one resin (A) which improves the wet strength thereof, and, optionally, at least one wet strength promoter (B), said paper pulp or said paper prepared therefrom having been treated with a composition (D) which comprises at least one polyorganosiloxane (C) containing, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom, the functional group V being a group with sterically hindered piperidinyl functional group(s) selected from the group consisting of the: (a) groups of formula (I):

in which formula R⁴ is a divalent hydrocarbonaceous radical selected from among: linear or branched alkylene radicals having 2 to 18 carbon atoms; alkylenecarbonyl radicals, the linear or branched alkylene moiety of which having 2 to 20 carbon atoms; alkylenecyclohexylene radicals, the linear or branched alkylene moiety of which having 2 to 12 carbon atoms and the cyclohexylene moiety of which comprises an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals, which may be identical or different, are each an alkylene radical having 1 to 12 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals are as defined above and one of them or both are substituted by one or two —OH group(s); radicals of formula —R⁷—COO—R⁷— in which the R⁷ radicals are as defined above; radicals of formula —R⁸—O—R⁹—O—CO—R⁸— in which the R⁸ and R⁹ radicals, which may be identical or different, are each an alkylene radical having 2 to 12 carbon atoms and the R⁹ radical is optionally substituted by a hydroxyl radical; U represents —O— or —NR¹⁰-, in which R¹⁰ is a hydrogen atom, a linear or branched alkyl radical having 1 to 6 carbon atoms or a divalent radical of formula:

in which R⁴ is as defined above, R⁵ and R⁶ are as defined below and R¹¹ is a linear or branched divalent alkylene radical having from 1 to 12 carbon atoms, one of the valency bonds (that of R¹¹) being connected to the atom of —NR¹⁰— and the other (that of R⁴) being connected to a silicon atom; the R⁵ radicals, which may be identical or different, are each a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; and the R⁶ radical is a hydrogen atom or R⁵ or 0; and (b) groups of formula (II):

in which formula R′⁴ is a trivalent radical of formula:

where m represents a number from 2 to 20, or a trivalent radical of formula:

where p represents a number from 2 to 20; U′ represents —O— or —NR¹²—, in which R¹² is a hydrogen atom or a linear or branched alkyl radical having 1 to 6 carbon atoms; and R⁵ and R⁶ have the same meanings as in formula (I).
 3. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, said at least one functional group V having the formula (I).
 4. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, said at least one functional group V having the formula (II).
 5. The water-resistant, repulpable and hydrophilic paper as defined by claim 2, said paper pulp having been treated with the composition (D).
 6. The water-resistant, repulpable and hydrophilic paper as defined by claim 2, the final paper having been treated with the composition (D).
 7. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, said at least one polyorganosiloxane comprising siloxyl structural units having the formula (III):

in which formula: (1) the symbols Z, which may be identical or different, represent R¹ and/or V; (2) the symbols R¹, R² and R³, which may be identical or different, each represent an optionally substituted, linear or branched C₁-C₁₂ alkyl radical, an optionally substituted C₅-C₁₀ cycloalkyl radical, an optionally substituted C₆-C₁₈ aryl radical, an optionally substituted aralkyl radical or an —OR¹³ radical wherein R¹³ represents a hydrogen atom, a linear, branched or cyclic alkyl radical having from 1 to 15 carbon atoms or a hydrocarbonaceous group comprising an epoxide and/or polyether functional group; (3) the symbols V are as defined above; and (4) the number of siloxyl units without a V group ranges from 1 and 800, the number of siloxyl units with a V group ranges from 1 and 20, and 0≦w≦10 and 8≦y≦798.
 8. The water-resistant, repulpable and hydrophilic paper as defined by claim 7, the polyorganosiloxane (C) of formula (III) being linear (w=0) and the symbols R¹, R² and R³ of the formula (III) being methyl radicals.
 9. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, wherein said polyorganosiloxane (C) having the formula (I) or (II), the radical R⁵ are methyl radicals.
 10. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, said at least one polyorganosiloxane comprising siloxyl structural units having the formula (IV):

in which formula: the various units are randomly distributed in the chain; p represents a number greater than or equal to 0; r represents a number greater than or equal to 0; q represents a number greater than or equal to 1; R′¹ represents a linear or branched alkyl radical having 1 to 18 carbon atoms; the U, R⁴ and R⁶ groups are as defined above.
 11. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, said at least one resin (A) comprising a polyamidoamine-epichlorohydrin (PAE) cationic resin.
 12. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, prepared from a cellulosic paper pulp.
 13. A process for the preparation of a water-resistant, repulpable and hydrophilic paper having a soft feel as defined by claims 1 or 2, comprising wet shaping a paper pulp thereof, said paper pulp or said paper prepared therefrom having been treated with a composition (D) which comprises at least one polyorganosiloxane (C) containing, per molecule, at least one siloxyl unit substituted by at least one functional group V directly bonded to a silicon atom, the functional group V being a group with sterically hindered piperidinyl functional group(s) selected from the group consisting of the: (a) groups of formula (I):

in which formula R⁴ is a divalent hydrocarbonaceous radical selected from among: linear or branched alkylene radicals having 2 to 18 carbon atoms; alkylenecarbonyl radicals, the linear or branched alkylene moiety of which having 2 to 20 carbon atoms; alkylenecyclohexylene radicals, the linear or branched alkylene moiety of which having 2 to 12 carbon atoms and the cyclohexylene moiety of which comprises an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals, which may be identical or different, are each an alkylene radical having 1 to 12 carbon atoms; radicals of formula —R⁷—O—R⁷— in which the R⁷ radicals are as defined above and one of them or both are substituted by one or two —OH group(s); radicals of formula —R⁷—COO—R⁷— in which the R⁷ radicals are as defined above; radicals of formula —R⁸—O—R⁹—O—CO—R⁸— in which the R⁸ and R⁹ radicals, which may be identical or different, are each an alkylene radical having 2 to 12 carbon atoms and the R⁹ radical is optionally substituted by a hydroxyl radical; U represents —O— or —NR¹⁰-, in which R¹⁰ is a hydrogen atom, a linear or branched alkyl radical having 1 to 6 carbon atoms or a divalent radical of formula:

in which R⁴ is as defined above, R⁵ and R⁶ are as defined below and R¹¹ is a linear or branched divalent alkylene radical having from 1 to 12 carbon atoms, one of the valency bonds (that of R¹¹) being connected to the atom of —NR¹⁰— and the other (that of R⁴) being connected to a silicon atom; the R⁵ radicals, which may be identical or different, are each a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; and the R⁶ radical is a hydrogen atom or R⁵ or 0; and (b) groups of formula (II):

in which formula R′⁴ is a trivalent radical of formula:

where m represents a number from 2 to 20, or a trivalent radical of formula:

where p represents a number from 2 to 20; U′ represents —O— or —NR¹²—, in which R¹² is a hydrogen atom or a linear or branched alkyl radical having 1 to 6 carbon atoms; and R⁵ and R⁶ have the same meanings as in formula (I).
 14. The process as defined by claim 13, said at least one resin (A) comprising a polyamidoamine-epichlorohydrin (PAE) cationic resin.
 15. The process as defined by claim 13, the paper having been prepared from a cellulosic pulp.
 16. The water-resistant, repulpable and hydrophilic paper as defined by claim 2, said composition (D) comprising an aqueous solution, dispersion or emulsion.
 17. The water-resistant, repulpable and hydrophilic paper as defined by claims 1 or 2, comprising a paper towel, toilet paper, household or sanitary absorbent paper, or paper handkerchief. 